1.
PubChem
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PubChem is a database of chemical molecules and their activities against biological assays. The system is maintained by the National Center for Biotechnology Information, a component of the National Library of Medicine, PubChem can be accessed for free through a web user interface. Millions of compound structures and descriptive datasets can be downloaded via FTP. PubChem contains substance descriptions and small molecules with fewer than 1000 atoms and 1000 bonds, more than 80 database vendors contribute to the growing PubChem database. PubChem consists of three dynamically growing primary databases, as of 28 January 2016, Compounds,82.6 million entries, contains pure and characterized chemical compounds. Substances,198 million entries, contains also mixtures, extracts, complexes, bioAssay, bioactivity results from 1.1 million high-throughput screening programs with several million values. PubChem contains its own online molecule editor with SMILES/SMARTS and InChI support that allows the import and export of all common chemical file formats to search for structures and fragments. In the text search form the database fields can be searched by adding the name in square brackets to the search term. A numeric range is represented by two separated by a colon. The search terms and field names are case-insensitive, parentheses and the logical operators AND, OR, and NOT can be used. AND is assumed if no operator is used, example,0,5000,50,10 -5,5 PubChem was released in 2004. The American Chemical Society has raised concerns about the publicly supported PubChem database and they have a strong interest in the issue since the Chemical Abstracts Service generates a large percentage of the societys revenue. To advocate their position against the PubChem database, ACS has actively lobbied the US Congress, soon after PubChems creation, the American Chemical Society lobbied U. S. Congress to restrict the operation of PubChem, which they asserted competes with their Chemical Abstracts Service

2.
ChemSpider
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ChemSpider is a database of chemicals. ChemSpider is owned by the Royal Society of Chemistry, the database contains information on more than 50 million molecules from over 500 data sources including, Each chemical is given a unique identifier, which forms part of a corresponding URL. This is an approach to develop an online chemistry database. The search can be used to widen or restrict already found results, structure searching on mobile devices can be done using free apps for iOS and for the Android. The ChemSpider database has been used in combination with text mining as the basis of document markup. The result is a system between chemistry documents and information look-up via ChemSpider into over 150 data sources. ChemSpider was acquired by the Royal Society of Chemistry in May,2009, prior to the acquisition by RSC, ChemSpider was controlled by a private corporation, ChemZoo Inc. The system was first launched in March 2007 in a release form. ChemSpider has expanded the generic support of a database to include support of the Wikipedia chemical structure collection via their WiChempedia implementation. A number of services are available online. SyntheticPages is an interactive database of synthetic chemistry procedures operated by the Royal Society of Chemistry. Users submit synthetic procedures which they have conducted themselves for publication on the site and these procedures may be original works, but they are more often based on literature reactions. Citations to the published procedure are made where appropriate. They are checked by an editor before posting. The pages do not undergo formal peer-review like a journal article. The comments are moderated by scientific editors. The intention is to collect practical experience of how to conduct useful chemical synthesis in the lab, while experimental methods published in an ordinary academic journal are listed formally and concisely, the procedures in ChemSpider SyntheticPages are given with more practical detail. Comments by submitters are included as well, other publications with comparable amounts of detail include Organic Syntheses and Inorganic Syntheses

3.
Chemical formula
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These are limited to a single typographic line of symbols, which may include subscripts and superscripts. A chemical formula is not a name, and it contains no words. Although a chemical formula may imply certain simple chemical structures, it is not the same as a full chemical structural formula. Chemical formulas can fully specify the structure of only the simplest of molecules and chemical substances, the simplest types of chemical formulas are called empirical formulas, which use letters and numbers indicating the numerical proportions of atoms of each type. Molecular formulas indicate the numbers of each type of atom in a molecule. For example, the formula for glucose is CH2O, while its molecular formula is C6H12O6. This is possible if the relevant bonding is easy to show in one dimension, an example is the condensed molecular/chemical formula for ethanol, which is CH3-CH2-OH or CH3CH2OH. For reasons of structural complexity, there is no condensed chemical formula that specifies glucose, chemical formulas may be used in chemical equations to describe chemical reactions and other chemical transformations, such as the dissolving of ionic compounds into solution. A chemical formula identifies each constituent element by its chemical symbol, in empirical formulas, these proportions begin with a key element and then assign numbers of atoms of the other elements in the compound, as ratios to the key element. For molecular compounds, these numbers can all be expressed as whole numbers. For example, the formula of ethanol may be written C2H6O because the molecules of ethanol all contain two carbon atoms, six hydrogen atoms, and one oxygen atom. Some types of compounds, however, cannot be written with entirely whole-number empirical formulas. An example is boron carbide, whose formula of CBn is a variable non-whole number ratio with n ranging from over 4 to more than 6.5. When the chemical compound of the consists of simple molecules. These types of formulas are known as molecular formulas and condensed formulas. A molecular formula enumerates the number of atoms to reflect those in the molecule, so that the formula for glucose is C6H12O6 rather than the glucose empirical formula. However, except for very simple substances, molecular chemical formulas lack needed structural information, for simple molecules, a condensed formula is a type of chemical formula that may fully imply a correct structural formula. For example, ethanol may be represented by the chemical formula CH3CH2OH

4.
Jmol
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Jmol is computer software for molecular modelling chemical structures in 3-dimensions. Jmol returns a 3D representation of a molecule that may be used as a teaching tool and it is written in the programming language Java, so it can run on the operating systems Windows, macOS, Linux, and Unix, if Java is installed. It is free and open-source software released under a GNU Lesser General Public License version 2.0, a standalone application and a software development kit exist that can be integrated into other Java applications, such as Bioclipse and Taverna. A popular feature is an applet that can be integrated into web pages to display molecules in a variety of ways, for example, molecules can be displayed as ball-and-stick models, space-filling models, ribbon diagrams, etc. Jmol supports a range of chemical file formats, including Protein Data Bank, Crystallographic Information File, MDL Molfile. There is also a JavaScript-only version, JSmol, that can be used on computers with no Java, the Jmol applet, among other abilities, offers an alternative to the Chime plug-in, which is no longer under active development. While Jmol has many features that Chime lacks, it does not claim to reproduce all Chime functions, most notably, Chime requires plug-in installation and Internet Explorer 6.0 or Firefox 2.0 on Microsoft Windows, or Netscape Communicator 4.8 on Mac OS9. Jmol requires Java installation and operates on a variety of platforms. For example, Jmol is fully functional in Mozilla Firefox, Internet Explorer, Opera, Google Chrome, fast and Scriptable Molecular Graphics in Web Browsers without Java3D

5.
Simplified molecular-input line-entry system
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The simplified molecular-input line-entry system is a specification in form of a line notation for describing the structure of chemical species using short ASCII strings. SMILES strings can be imported by most molecule editors for conversion back into two-dimensional drawings or three-dimensional models of the molecules, the original SMILES specification was initiated in the 1980s. It has since modified and extended. In 2007, a standard called OpenSMILES was developed in the open-source chemistry community. Other linear notations include the Wiswesser Line Notation, ROSDAL and SLN, the original SMILES specification was initiated by David Weininger at the USEPA Mid-Continent Ecology Division Laboratory in Duluth in the 1980s. The Environmental Protection Agency funded the project to develop SMILES. It has since modified and extended by others, most notably by Daylight Chemical Information Systems. In 2007, a standard called OpenSMILES was developed by the Blue Obelisk open-source chemistry community. Other linear notations include the Wiswesser Line Notation, ROSDAL and SLN, in July 2006, the IUPAC introduced the InChI as a standard for formula representation. SMILES is generally considered to have the advantage of being slightly more human-readable than InChI, the term SMILES refers to a line notation for encoding molecular structures and specific instances should strictly be called SMILES strings. However, the term SMILES is also used to refer to both a single SMILES string and a number of SMILES strings, the exact meaning is usually apparent from the context. The terms canonical and isomeric can lead to confusion when applied to SMILES. The terms describe different attributes of SMILES strings and are not mutually exclusive, typically, a number of equally valid SMILES strings can be written for a molecule. For example, CCO, OCC and CC all specify the structure of ethanol, algorithms have been developed to generate the same SMILES string for a given molecule, of the many possible strings, these algorithms choose only one of them. This SMILES is unique for each structure, although dependent on the algorithm used to generate it. These algorithms first convert the SMILES to a representation of the molecular structure. A common application of canonical SMILES is indexing and ensuring uniqueness of molecules in a database, there is currently no systematic comparison across commercial software to test if such flaws exist in those packages. SMILES notation allows the specification of configuration at tetrahedral centers, and these are structural features that cannot be specified by connectivity alone and SMILES which encode this information are termed isomeric SMILES

6.
International Chemical Identifier
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Initially developed by IUPAC and NIST from 2000 to 2005, the format and algorithms are non-proprietary. The continuing development of the standard has supported since 2010 by the not-for-profit InChI Trust. The current version is 1.04 and was released in September 2011, prior to 1.04, the software was freely available under the open source LGPL license, but it now uses a custom license called IUPAC-InChI Trust License. Not all layers have to be provided, for instance, the layer can be omitted if that type of information is not relevant to the particular application. InChIs can thus be seen as akin to a general and extremely formalized version of IUPAC names and they can express more information than the simpler SMILES notation and differ in that every structure has a unique InChI string, which is important in database applications. Information about the 3-dimensional coordinates of atoms is not represented in InChI, the InChI algorithm converts input structural information into a unique InChI identifier in a three-step process, normalization, canonicalization, and serialization. The InChIKey, sometimes referred to as a hashed InChI, is a fixed length condensed digital representation of the InChI that is not human-understandable. The InChIKey specification was released in September 2007 in order to facilitate web searches for chemical compounds and it should be noted that, unlike the InChI, the InChIKey is not unique, though collisions can be calculated to be very rare, they happen. In January 2009 the final 1.02 version of the InChI software was released and this provided a means to generate so called standard InChI, which does not allow for user selectable options in dealing with the stereochemistry and tautomeric layers of the InChI string. The standard InChIKey is then the hashed version of the standard InChI string, the standard InChI will simplify comparison of InChI strings and keys generated by different groups, and subsequently accessed via diverse sources such as databases and web resources. Every InChI starts with the string InChI= followed by the version number and this is followed by the letter S for standard InChIs. The remaining information is structured as a sequence of layers and sub-layers, the layers and sub-layers are separated by the delimiter / and start with a characteristic prefix letter. The six layers with important sublayers are, Main layer Chemical formula and this is the only sublayer that must occur in every InChI. The atoms in the formula are numbered in sequence, this sublayer describes which atoms are connected by bonds to which other ones. Describes how many hydrogen atoms are connected to each of the other atoms, the condensed,27 character standard InChIKey is a hashed version of the full standard InChI, designed to allow for easy web searches of chemical compounds. Most chemical structures on the Web up to 2007 have been represented as GIF files, the full InChI turned out to be too lengthy for easy searching, and therefore the InChIKey was developed. With all databases currently having below 50 million structures, such duplication appears unlikely at present, a recent study more extensively studies the collision rate finding that the experimental collision rate is in agreement with the theoretical expectations. Example, Morphine has the structure shown on the right, as the InChI cannot be reconstructed from the InChIKey, an InChIKey always needs to be linked to the original InChI to get back to the original structure

7.
Natural product
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A natural product is a chemical compound or substance produced by a living organism—that is, found in nature. In the broadest sense, natural products include any substance produced by life, natural products can also be prepared by chemical synthesis and have played a central role in the development of the field of organic chemistry by providing challenging synthetic targets. The term natural product has also extended for commercial purposes to refer to cosmetics, dietary supplements. Within the field of chemistry, the definition is often further restricted to secondary metabolites. Secondary metabolites are not essential for survival, but nevertheless provide organisms that produce them an evolutionary advantage, many secondary metabolites are cytotoxic and have been selected and optimized through evolution for use as chemical warfare agents against prey, predators, and competing organisms. Natural products sometimes have pharmacological or biological activity that can be of benefit in treating diseases. As such, natural products are the active components not only of most traditional medicines, in fact, natural products are the inspiration for approximately one half of U. S. Food and Drug Administration-approved drugs. The broadest definition of natural product is anything that is produced by life, and includes the likes of biotic materials, bio-based materials, bodily fluids, a more restrictive definition of a natural product is an organic compound that is synthesized by a living organism. The remainder of this article restricts itself to this more narrow definition, natural products may be classified according to their biological function, biosynthetic pathway, or source as described below. Following Albrecht Kossels original proposal in 1891, natural products are divided into two major classes, the primary and secondary metabolites. Primary metabolites have a function that is essential to the survival of the organism that produces them. Secondary metabolites in contrast have a function that mainly affects other organisms. Secondary metabolites are not essential to survival but do increase the competitiveness of the organism within its environment, because of their ability to modulate biochemical and signal transduction pathways, some secondary metabolites have useful medicinal properties. Natural products especially within the field of chemistry are often defined as primary and secondary metabolites. A more restrictive definition limiting natural products to secondary metabolites is commonly used within the fields of medicinal chemistry, primary metabolites as defined by Kossel are components of basic metabolic pathways that are required for life. They are associated with cellular functions such as nutrient assimilation, energy production. They have a species distribution that span many phyla and frequently more than one kingdom. Primary metabolites include carbohydrates, lipids, amino acids, and nucleic acids which are the building blocks of life

8.
Steroid
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A steroid is an organic compound with four rings arranged in a specific configuration. Examples include the dietary lipid cholesterol, the sex hormones estradiol and testosterone, the steroid core structure is composed of seventeen carbon atoms, bonded in four fused rings, three six-member cyclohexane rings and one five-member cyclopentane ring. Steroids vary by the groups attached to this four-ring core. Sterols are forms of steroids with a group at position three and a skeleton derived from cholestane. They can also vary more markedly by changes to the ring structure, hundreds of steroids are found in plants, animals and fungi. All steroids are manufactured in cells from the sterols lanosterol or cycloartenol, lanosterol and cycloartenol are derived from the cyclization of the triterpene squalene. The three cyclohexane rings form the skeleton of a derivative of phenanthrene. The D ring has a cyclopentane structure, when the two methyl groups and eight carbon side chains are present, the steroid is said to have a cholestane framework. The following are some categories of steroids. In eukaryotes, steroids are found in fungi, animals, animal steroids include compounds of vertebrate and insect origin, the latter including ecdysteroids such as ecdysterone. Steroid hormones include, Sex hormones, which influence sex differences and these include androgens, estrogens, and progestagens. In popular use, the term often refers to anabolic steroids. Plant steroids include steroidal alkaloids found in Solanaceae, the phytosterols, in prokaryotes, biosynthetic pathways exist for the tetracyclic steroid framework – where its origin from eukaryotes is conjectured – and the more-common pentacyclic triterpinoid hopanoid framework. One example of how MeSH performs this classification is available at the Wikipedia MeSH catalog, examples of this classification include, The gonane is the parent 17-carbon tetracyclic hydrocarbon molecule with no alkyl sidechains. Secosteroids are a subclass of steroidal compounds resulting, biosynthetically or conceptually, major secosteroid subclasses are defined by the steroid carbon atoms where this scission has taken place. Norsteroids and homosteroids are structural subclasses of steroids formed from biosynthetic steps, the former involves enzymic ring expansion-contraction reactions, and the latter is accomplished or through ring closures of acyclic precursors with more ring atoms than the parent steroid framework. Combinations of these alterations are known in nature. Ingestion of these C-nor-D-homosteroids results in defects in lambs, cyclopia from cyclopamine

9.
Equus (genus)
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Equus is a genus of mammals in the family Equidae, which includes horses, asses, and zebras. Within Equidae, Equus is the only recognized extant genus, comprising seven living species, the term equine refers to any member of this genus, including horses. Like Equidae more broadly, Equus has numerous species known only from fossils. The genus most likely originated in North America and spread quickly to the Old World, Equines are odd-toed ungulates with slender legs, long heads, relatively long necks, manes and long tails. All species are herbivorous, and mostly grazers with simpler digestive systems than ruminants, while the domestic horse and donkey exist worldwide, wild equine populations are limited to Africa and Asia. In both systems, females take care of their offspring but males may play a role as well, Equines communicate with each other both visually and vocally. Human activities have threatened wild equine populations and out of the seven living species, only the plains zebra remains widespread and abundant. The word equus is Latin for horse, and is cognate with the Greek ἵππος, horse, and Mycenaean Greek i-qo /ikkʷos/, the genus Equus was first described by Carl Linnaeus in 1758. It is the only recognized extant genus in the family Equidae, the first equids were small, dog-sized mammals adapted for browsing on shrubs during the Eocene, around 54 million years ago. These animals had three toes on the feet and four on the front feet with small hooves in place of claws. Equids developed into larger, three-toed animals during the Oligocene and Miocene, from there, the tridactyl toes became progressively smaller through the Pleistocene until the emergence of the single-toed Equus. The genus Equus, which all extant equines, is believed to have evolved from Dinohippus. One of the oldest species is Equus simplicidens, described as zebra-like with a head shape. The oldest material to date was found in Idaho, USA, the genus appears to have spread quickly into the Old World, with the similarly aged E. livenzovensis documented from western Europe and Russia. Molecular phylogenies indicate that the most recent common ancestor of all modern equines lived ~5.6 mya, mitochondrial evidence supports the division of Equus species into non-caballoid and caballoids or true horses. Of the extant equine species, the lineage of the asses may have diverged first, zebras appear to be monophyletic and differentiated in Africa where they are endemic. Molecular dating indicates the caballoid lineage diverged from the non-caballoids 4 mya, genetic results suggest that all North American fossils of caballine equines, as well as South American fossils traditionally placed in the subgenus E. belong to E. ferus. Remains attributed to a variety of species and lumped together as New World stilt-legged horses probably all belong to a species that was endemic to North America

10.
Equilin
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Equilin, also known as 7-dehydroestrone, as well as estra-1,3,5, 7-tetraen-3-ol-17-one, is an estrogen from horses. Equilin is one of the present in the mixture of estrogens isolated from horse urine. Premarin became the most commonly used form of estrogen for hormone replacement therapy in the United States of America, estrone is the major estrogen in Premarin and equilin is present as about 25% of the total. Estrone is an estrogen that is normally found in women. Equilin is not normally present in women, so there has been interest in the effects of equilin on the human body, the estrogens in Premarin are present mainly as conjugates, modified chemical forms in which the active estrogen is coupled to another chemical group such as sulfate. Estrone sulfate is usually the form of estrogen in women. After being taken into a body, the conjugated estrogens of Premarin are converted to the active unconjugated estrogens or excreted from the womans body. Estrone can be converted to estradiol, which is thought to be the active estrogen in women. Equilenin 17α-Dihydroequilin 17β-Dihydroequilin 17α-Dihydroequilenin 17β-Dihydroequilenin 8, 9-Dehydroestrone 8, 9-Dehydroestradiol

11.
Alfatradiol
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Alfatradiol, also known as 17α-estradiol or as 17-epiestradiol, is a steroidal weak estrogen and potent 5α-reductase inhibitor used topically in the treatment of androgenic alopecia in men and women. It is a stereoisomer of the steroid hormone 17β-estradiol. Alfatradiol is used in form of a solution for topical application on the scalp. Similarly to other drugs against alopecia, topical or oral, it has to be applied continuously to prevent further hair loss, regrowth of hair that was already lost is only possible to a limited extent. In general, advanced alopecia does not respond well to medical treatment, a university-led study in 103 women comparing alfatradiol to minoxidil, another topical hair loss treatment, found the latter to be more effective. In contrast to minoxidil, alfatradiol did not result in an increase of density or thickness. In an earlier study, no side effects were noted. Nothing is known about the use of alfatradiol during pregnancy or lactation, the package leaflet recommends against using it under these circumstances. Local burning or itching is not an effect of alfatradiol, the solution can stimulate sebum production. Alfatradiol is distinguished from estradiol, the predominant sex hormone in females, in contrast to 17β-estradiol, 17α-estradiol, while it still binds to the estrogen receptor, has less or no feminizing estrogen activity depending on its dosage and the tissue it is affecting. Alfatradiol acts as an inhibitor of the enzyme 5α-reductase, which is responsible for the activation of testosterone to dihydrotestosterone, 17α-Estradiol has been studied as a therapeutic with potential to treat Alzheimers and Parkinsons disease and other patients suffering from neurodegenerative diseases. 17α-Estradiol is a component of hormone replacement products, which have been studied and/or marketed in women and men since the 1930s. A survey of the effects of various forms of 17α-estradiol in humans on biochemical parameters, efficacy, estrogenicity, metabolism, safety, alfatradiol binds to the ERα and ERβ with 58% and 11% of the relative binding affinity of 17β-estradiol. However, it has 100-fold lower estrogenic activity relative to estradiol, alfatradiol/dexamethasone Estradiol 17alpha-dehydrogenase Finasteride Ketoconazole Minoxidil 17α-Epiestriol Epimestrol

12.
Sulfate
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The sulfate or sulphate ion is a polyatomic anion with the empirical formula SO2−4. Sulfate is the spelling recommended by IUPAC, but sulphate is used in British English, salts, acid derivatives, and peroxides of sulfate are widely used in industry. Sulfates occur widely in everyday life, sulfates are salts of sulfuric acid and many are prepared from that acid. The sulfate anion consists of a sulfur atom surrounded by four equivalent oxygen atoms in a tetrahedral arrangement. The symmetry is the same as that of methane, the sulfur atom is in the +6 oxidation state while the four oxygen atoms are each in the state. The sulfate ion carries a charge of −2 and it is the conjugate base of the bisulfate ion, HSO−4. Organic sulfate esters, such as sulfate, are covalent compounds. The tetrahedral molecular geometry of the ion is as predicted by VSEPR theory. Later, Linus Pauling used valence bond theory to propose that the most significant resonance canonicals had two pi bonds involving d orbitals and his reasoning was that the charge on sulfur was thus reduced, in accordance with his principle of electroneutrality. The S−O bond length of 149 pm is shorter than the bond lengths in sulfuric acid of 157 pm for S−OH, the double bonding was taken by Pauling to account for the shortness of the S−O bond. Paulings use of d orbitals provoked a debate on the importance of π bonding. The outcome was a consensus that d orbitals play a role. A widely accepted description involving pπ – dπ bonding was initially proposed by D. W. J. Cruickshank, in this model, fully occupied p orbitals on oxygen overlap with empty sulfur d orbitals. However, in description, despite there being some π character to the S−O bonds. For sulfuric acid, computational analysis confirms a positive charge on sulfur. Therefore, the representation with four single bonds is the optimal Lewis structure rather than the one with two double bonds, in this model, the structure obeys the octet rule and the charge distribution is in agreement with the electronegativity of the atoms. However, the representation of Pauling for sulfate and other main group compounds with oxygen is still a common way of representing the bonding in many textbooks. On the other hand, in the structure with an ionic bond, exceptions include calcium sulfate, strontium sulfate, lead sulfate, and barium sulfate, which are poorly soluble

13.
Ester
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In chemistry, esters are chemical compounds derived from an acid in which at least one –OH group is replaced by an –O–alkyl group. Usually, esters are derived from an acid and an alcohol. Glycerides, which are fatty acid esters of glycerol, are important esters in biology, being one of the classes of lipids. Esters with low weight are commonly used as fragrances and found in essential oils. Phosphoesters form the backbone of DNA molecules, nitrate esters, such as nitroglycerin, are known for their explosive properties, while polyesters are important plastics, with monomers linked by ester moieties. The word ester was coined in 1848 by German chemist Leopold Gmelin, probably as a contraction of the German Essigäther, ester names are derived from the parent alcohol and the parent acid, where the latter may be organic or inorganic. Esters derived from more complex carboxylic acids are, on the hand, more frequently named using the systematic IUPAC name. For example, the ester hexyl octanoate, also known under the trivial name hexyl caprylate, has the formula CH36CO25CH3, the chemical formulas of organic esters usually take the form RCO2R′, where R and R′ are the hydrocarbon parts of the carboxylic acid and the alcohol, respectively. For example, butyl acetate, derived from butanol and acetic acid would be written CH3CO2C4H9, alternative presentations are common including BuOAc and CH3COOC4H9. Cyclic esters are called lactones, regardless of whether they are derived from an organic or an inorganic acid, one example of a lactone is γ-valerolactone. An uncommon class of organic esters are the orthoesters, which have the formula RC3, triethylorthoformate is derived, in terms of its name from orthoformic acid and ethanol. Esters can also be derived from an acid and an alcohol. For example, triphenyl phosphate is the derived from phosphoric acid. Organic carbonates are derived from acid, for example, ethylene carbonate is derived from carbonic acid. So far an alcohol and inorganic acid are linked via oxygen atoms, in corollary, boron features borinic esters, boronic esters, and borates. As oxygen is a group 16 chemical element, sulfur atoms can replace some oxygen atoms in carbon–oxygen–central inorganic atom covalent bonds of an ester, esters contain a carbonyl center, which gives rise to 120 ° C–C–O and O–C–O angles. Unlike amides, esters are structurally flexible functional groups because rotation about the C–O–C bonds has a low barrier and their flexibility and low polarity is manifested in their physical properties, they tend to be less rigid and more volatile than the corresponding amides. The pKa of the alpha-hydrogens on esters is around 25, the preference for the Z conformation is influenced by the nature of the substituents and solvent, if present

14.
Sodium
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Sodium is a chemical element with symbol Na and atomic number 11. It is a soft, silvery-white, highly reactive metal, Sodium is an alkali metal, being in group 1 of the periodic table, because it has a single electron in its outer shell that it readily donates, creating a positively charged atom—the Na+ cation. Its only stable isotope is 23Na, the free metal does not occur in nature, but must be prepared from compounds. Sodium is the sixth most abundant element in the Earths crust, Sodium was first isolated by Humphry Davy in 1807 by the electrolysis of sodium hydroxide. Among many other useful compounds, sodium hydroxide is used in soap manufacture, and sodium chloride is a de-icing agent. Sodium is an element for all animals and some plants. Sodium ions are the major cation in the fluid and as such are the major contributor to the ECF osmotic pressure. Loss of water from the ECF compartment increases the sodium concentration, isotonic loss of water and sodium from the ECF compartment decreases the size of that compartment in a condition called ECF hypovolemia. In nerve cells, the charge across the cell membrane enables transmission of the nerve impulse—an action potential—when the charge is dissipated. The melting and boiling points of sodium are lower than those of lithium but higher than those of the alkali metals potassium, rubidium. All of these high-pressure allotropes are insulators and electrides.3 nm, spin-orbit interactions involving the electron in the 3p orbital split the D line into two, at 589.0 and 589.6 nm, hyperfine structures involving both orbitals cause many more lines. Twenty isotopes of sodium are known, but only 23Na is stable, 23Na is created in the carbon-burning process in stars by fusing two carbon atoms together, this requires temperatures above 600 megakelvins and a star of at least three solar masses. Two nuclear isomers have been discovered, the one being 24mNa with a half-life of around 20.2 milliseconds. Sodium atoms have 11 electrons, one more than the stable configuration of the noble gas neon. This process requires so little energy that sodium is oxidized by giving up its 11th electron. In contrast, the ionization energy is very high, because the 10th electron is closer to the nucleus than the 11th electron. As a result, sodium usually forms ionic compounds involving the Na+ cation, the most common oxidation state for sodium is +1. It is generally less reactive than potassium and more reactive than lithium, Sodium metal is highly reducing, with the reduction of sodium ions requiring −2.71 volts, though potassium and lithium have even more negative potentials

15.
Salt (chemistry)
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In chemistry, a salt is an ionic compound that results from the neutralization reaction of an acid and a base. Salts are composed of related numbers of cations and anions so that the product is electrically neutral and these component ions can be inorganic, such as chloride, or organic, such as acetate, and can be monatomic, such as fluoride, or polyatomic, such as sulfate. There are several varieties of salts, salts that hydrolyze to produce hydroxide ions when dissolved in water are alkali salts, whilst those that hydrolyze to produce hydronium ions in water are acidic salts. Neutral salts are those salts that are neither acidic nor basic, zwitterions contain an anionic centre and a cationic centre in the same molecule, but are not considered to be salts. Examples of zwitterions include amino acids, many metabolites, peptides, usually, non-dissolved salts at standard conditions for temperature and pressure are solid, but there are exceptions. Molten salts and solutions containing dissolved salts are called electrolytes, as they are able to conduct electricity. As observed in the cytoplasm of cells, in blood, urine, plant saps and mineral waters, therefore, their salt content is given for the respective ions. Salts can appear to be clear and transparent, opaque, and even metallic, in many cases, the apparent opacity or transparency are only related to the difference in size of the individual monocrystals. Since light reflects from the boundaries, larger crystals tend to be transparent. The color of the salt is due to the electronic structure in the d-orbitals of transition elements or in the conjugated organic dye framework. Different salts can elicit all five basic tastes, e. g. salty, sweet, sour, bitter, and umami or savory. Salts of strong acids and strong bases are non-volatile and odorless and that slow, partial decomposition is usually accelerated by the presence of water, since hydrolysis is the other half of the reversible reaction equation of formation of weak salts. Many ionic compounds can be dissolved in water or other similar solvents, the exact combination of ions involved makes each compound have a unique solubility in any solvent. The solubility is dependent on how well each ion interacts with the solvent, for example, all salts of sodium, potassium and ammonium are soluble in water, as are all nitrates and many sulfates – barium sulfate, calcium sulfate and lead sulfate are examples of exceptions. However, ions that bind tightly to each other and form highly stable lattices are less soluble, for example, most carbonate salts are not soluble in water, such as lead carbonate and barium carbonate. Some soluble carbonate salts are, sodium carbonate, potassium carbonate, solid salts do not conduct electricity. Moreover, solutions of salts also conduct electricity, the name of a salt starts with the name of the cation followed by the name of the anion. Salts are often referred to only by the name of the cation or by the name of the anion. g

16.
Pharmaceutical drug
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A pharmaceutical drug is a drug used to diagnose, cure, treat, or prevent disease. Drug therapy is an important part of the field and relies on the science of pharmacology for continual advancement. Drugs are classified in various ways, one of the key divisions is by level of control, which distinguishes prescription drugs from over-the-counter drugs. Other ways to classify medicines are by mode of action, route of administration, biological system affected, an elaborate and widely used classification system is the Anatomical Therapeutic Chemical Classification System. The World Health Organization keeps a list of essential medicines, Drug discovery and drug development are complex and expensive endeavors undertaken by pharmaceutical companies, academic scientists, and governments. Governments generally regulate what drugs can be marketed, how drugs are marketed, controversies have arisen over drug pricing and disposal of used drugs. In the US, a drug is, A substance recognized by an official pharmacopoeia or formulary, a substance intended for use in the diagnosis, cure, mitigation, treatment, or prevention of disease. A substance intended to affect the structure or any function of the body, a substance intended for use as a component of a medicine but not a device or a component, part or accessory of a device. Pharmaceutical or a drug is classified on the basis of their origin, Drug from natural origin, Herbal or plant or mineral origin, some drug substances are of marine origin. Drug from chemical as well as origin, Derived from partial herbal and partial chemical synthesis Chemical. Drug derived from animal origin, For example, hormones, Drug derived from microbial origin, Antibiotics Drug derived by biotechnology genetic-engineering, hybridoma technique for example Drug derived from radioactive substances. An elaborate and widely used system is the Anatomical Therapeutic Chemical Classification System. The World Health Organization keeps a list of essential medicines, the main classes of painkillers are NSAIDs, opioids and Local anesthetics. For consciousness Some anesthetics include Benzodiazepines and Barbiturates, the main categories of drugs for musculoskeletal disorders are, NSAIDs, muscle relaxants, neuromuscular drugs, and anticholinesterases. Euthanasia is not permitted by law in countries, and consequently medicines will not be licensed for this use in those countries. Administration is the process by which a patient takes a medicine, there are three major categories of drug administration, enteral, parenteral, and other. It can be performed in various forms such as pills, tablets. There are many variations in the routes of administration, including intravenous and they can be administered all at once as a bolus, at frequent intervals or continuously

17.
Extract
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An extract is a substance made by extracting a part of a raw material, often by using a solvent such as ethanol or water. Extracts may be sold as tinctures or in powder form, the aromatic principles of many spices, nuts, herbs, fruits, etc. Absorption is generally accomplished by steeping in alcohol, as vanilla beans, maceration is used to create smaller bits of the whole, as in making peppermint extract, etc. Distillation is used with maceration, but in cases, it requires expert chemical knowledge. The most important among those that lend themselves to pure extract manufacture include lemons, oranges, the majority of concentrated fruit flavors such as banana, cherry, peach, pineapple, raspberry and strawberry, are produced by combining a variety of esters with special oils. The desired colors are obtained by the use of dyes. Among the esters most generally employed are ethyl acetate and ethyl butyrate, the chief factors in the production of artificial banana, pineapple, and strawberry extract are amyl acetate and amyl butyrate. Artificial extracts generally do not possess the delicacy of natural fruit flavor, vanilla extract Spagyric This article incorporates text from a publication now in the public domain, Ward, Artemas

18.
Urine
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Urine is a liquid by-product of metabolism in the bodies of many animals, including humans. It is expelled from the kidneys and flows through the ureters to the urinary bladder, cellular metabolism generates numerous by-products, many nitrogenous, that require clearance from the bloodstream. These by-products are eventually expelled from the body during urination, the method for excreting water-soluble chemicals from the body. These chemicals can be detected and analyzed by urinalysis, of the many such substances that exist, the three main nitrogenous wastes of the mammalian body are urea, uric acid, and creatinine. Animal urine forms part of the nitrogen cycle, in balanced ecosystems it fertilizes soil and plants, which in turn continue to support the animal population. Some animals use it to mark their territories, human urine and human feces are collectively referred to as human waste, as sewage, they require sewage treatment in places where population density is high. Livestock urine and feces similarly require proper management if the population density is high. Such management is part of ecological sanitation, most animals have excretory systems for elimination of soluble toxic wastes. In humans, soluble wastes are excreted primarily by the system and, to a lesser extent in terms of urea. The urinary system consists of the kidneys, ureters, urinary bladder, the system produces urine by a process of filtration, reabsorption, and tubular secretion. The kidneys extract the soluble wastes from the bloodstream, as well as water, sugars. The resulting urine contains high concentrations of urea and other substances, urine flows from the kidney through the ureter, bladder, and finally the urethra before passing from the body. Research looking at the duration of urination in a range of species found that 9 larger species urinated for 21 ±13 seconds irrespective of body size. Smaller species including rodents and bats cannot produce jets and instead urinate with a series of drops, producing too much or too little urine needs medical attention. Polyuria is a condition of excessive production of urine, oliguria when <400 mL are produced, about 91-96% of urine consists of water. Urine also contains an assortment of inorganic salts and organic compounds, including proteins, hormones, the total solids in urine are on average 59 g per person per day. Organic matter makes up between 65% and 85% of urine dry solids, with volatile solids comprising 75–85% of total solids, urea is the largest constituent of the solids, constituting more than 50% of the total. On an elemental level, human urine contains 6.87 g/L carbon,8.12 g/L nitrogen,8.25 g/L oxygen, the exact proportions vary with individuals and with factors such as diet and health

19.
Mare
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A mare is an adult female horse or other equine. In most cases, a mare is a horse over the age of three, and a filly is a female horse three and younger. In Thoroughbred horse racing, a mare is defined as a horse more than four years old. The word can also be used for other female equine animals, particularly mules and zebras, a broodmare is a mare used for breeding. A horses female parent is known as its dam, an uncastrated adult male horse is called a stallion and a castrated male is a gelding. Occasionally, the horse is used to designate only a male horse. Mares carry their young for approximately 11 months from conception to birth, usually just one young is born, twins are rare. When a domesticated mare foals, she nurses the foal for at least four to six months before it is weaned, the estrous cycle, also known as season or heat of a mare occurs roughly every 19–22 days and occurs from early spring into autumn. As the days shorten, most mares enter a period during the winter. The reproductive cycle in a mare is controlled by the photoperiod, as the days shorten, the mare returns to the anestrus period when she is not sexually receptive. However, for most competitive purposes, foals are given a birthday of January 1. Therefore, many breeding farms begin to put mares under lights in late winter in order to bring out of anestrus early. One exception to this rule is the field of endurance riding. Fillies are sexually mature by age two and are bred at that age, but generally should not be bred until they themselves have stopped growing. A healthy, well-managed mare can produce a foal every year into her twenties, in addition, some mares become anxious when separated from their foals, even temporarily, and thus are difficult to manage under saddle until their foals are weaned. Mares are considered easier to handle than stallions, however, geldings have little to no hormone-driven behavior patterns at all, thus sometimes they are preferred to both mares and stallions. Mares have a notorious, if generally undeserved, reputation for being marish, however, there is considerable evidence that much marish behavior is mostly the result of humans expecting or allowing the mare to misbehave. Because horses in general are very attuned to the state of their riders, expectation by a rider of difficult manners during estrus can create a self-fulfilling prophecy

20.
International Standard Book Number
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The International Standard Book Number is a unique numeric commercial book identifier. An ISBN is assigned to each edition and variation of a book, for example, an e-book, a paperback and a hardcover edition of the same book would each have a different ISBN. The ISBN is 13 digits long if assigned on or after 1 January 2007, the method of assigning an ISBN is nation-based and varies from country to country, often depending on how large the publishing industry is within a country. The initial ISBN configuration of recognition was generated in 1967 based upon the 9-digit Standard Book Numbering created in 1966, the 10-digit ISBN format was developed by the International Organization for Standardization and was published in 1970 as international standard ISO2108. Occasionally, a book may appear without a printed ISBN if it is printed privately or the author does not follow the usual ISBN procedure, however, this can be rectified later. Another identifier, the International Standard Serial Number, identifies periodical publications such as magazines, the ISBN configuration of recognition was generated in 1967 in the United Kingdom by David Whitaker and in 1968 in the US by Emery Koltay. The 10-digit ISBN format was developed by the International Organization for Standardization and was published in 1970 as international standard ISO2108, the United Kingdom continued to use the 9-digit SBN code until 1974. The ISO on-line facility only refers back to 1978, an SBN may be converted to an ISBN by prefixing the digit 0. For example, the edition of Mr. J. G. Reeder Returns, published by Hodder in 1965, has SBN340013818 -340 indicating the publisher,01381 their serial number. This can be converted to ISBN 0-340-01381-8, the check digit does not need to be re-calculated, since 1 January 2007, ISBNs have contained 13 digits, a format that is compatible with Bookland European Article Number EAN-13s. An ISBN is assigned to each edition and variation of a book, for example, an ebook, a paperback, and a hardcover edition of the same book would each have a different ISBN. The ISBN is 13 digits long if assigned on or after 1 January 2007, a 13-digit ISBN can be separated into its parts, and when this is done it is customary to separate the parts with hyphens or spaces. Separating the parts of a 10-digit ISBN is also done with either hyphens or spaces, figuring out how to correctly separate a given ISBN number is complicated, because most of the parts do not use a fixed number of digits. ISBN issuance is country-specific, in that ISBNs are issued by the ISBN registration agency that is responsible for country or territory regardless of the publication language. Some ISBN registration agencies are based in national libraries or within ministries of culture, in other cases, the ISBN registration service is provided by organisations such as bibliographic data providers that are not government funded. In Canada, ISBNs are issued at no cost with the purpose of encouraging Canadian culture. In the United Kingdom, United States, and some countries, where the service is provided by non-government-funded organisations. Australia, ISBNs are issued by the library services agency Thorpe-Bowker

21.
Antiestrogen
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Antiestrogens, also known as estrogen antagonists or estrogen blockers, are a class of drugs which prevent estrogens like estradiol from mediating their biological effects in the body. They act by blocking the estrogen receptor and/or inhibiting or suppressing estrogen production, antiestrogens are one of three types of sex hormone antagonists, the others being antiandrogens and antiprogestogens. Although aromatase inhibitors and antigonadotropins can be considered antiestrogens by some definitions, aromatase inhibitors and antigonadotropins reduce the production of estrogen, while the term antiestrogen is often reserved for agents reducing the response to estrogen. Antiestrogens are mainly used as a means of estrogen deprivation therapy in the treatment of ER-positive breast cancer and they are also used to treat infertility, male hypogonadism, and gynecomastia and are used as a component of hormone replacement therapy for transgender men. Side effects of antiestrogens include hot flashes, osteoporosis, breast atrophy, ethamoxytriphetol was the first antiestrogen to be discovered, followed by clomifene and tamoxifen. This article incorporates public domain material from the U. S. National Cancer Institute document Dictionary of Cancer Terms

22.
Estrogen receptor
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Estrogen receptors are a group of proteins found inside and on cells. They are receptors that are activated by the hormone estrogen and this article refers to the former. Once activated by estrogen, the ER is able to translocate into the nucleus, however, it also has additional functions independent of DNA binding. As hormone receptors for sex steroids, ERs, androgen receptors, there are two different forms of the estrogen receptor, usually referred to as α and β, each encoded by a separate gene. Hormone-activated estrogen receptors form dimers, and, since the two forms are coexpressed in many types, the receptors may form ERα or ERβ homodimers or ERαβ heterodimers. Estrogen receptor alpha and beta show significant overall sequence homology, the N-terminal A/B domain is able to transactivate gene transcription in the absence of bound ligand. While this region is able to activate gene transcription without ligand, the C domain, also known as the DNA-binding domain, binds to estrogen response elements in DNA. The D domain is a region that connects the C and E domains. The E domain contains the binding cavity as well as binding sites for coactivator and corepressor proteins. The E-domain in the presence of ligand is able to activate gene transcription. The C-terminal F domain function is not entirely clear and is variable in length, due to alternative RNA splicing, several ER isoforms are known to exist. At least three ERα and five ERβ isoforms have been identified, the ERβ isoforms receptor subtypes can transactivate transcription only when a heterodimer with the functional ERß1 receptor of 59 kDa is formed. The ERß3 receptor was detected at levels in the testis. The two other ERα isoforms are 36 and 46kDa, only in fish, but not in humans, an ERγ receptor has been described. In humans, the two forms of the receptor are encoded by different genes, ESR1 and ESR2 on the sixth and fourteenth chromosome. In males, ERα protein is found in the epithelium of the efferent ducts, the expression of the ERβ protein has been documented in ovarian granulosa cells, kidney, brain, bone, heart, lungs, intestinal mucosa, prostate, and endothelial cells. The ERα primary transcript gives rise to several alternatively spliced variants of unknown function, the ERs helix 12 domain plays a crucial role in determining interactions with coactivators and corepressors and, therefore, the respective agonist or antagonist effect of the ligand. In addition, the different estrogen receptor combinations may respond differently to various ligands, the ratio of α- to β- subtype concentration has been proposed to play a role in certain diseases

23.
Androgen
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This includes the activity of the primary male sex organs and development of male secondary sex characteristics. Androgens were first discovered in 1936, androgens increase in both boys and girls during puberty. Androgens are also the original anabolic steroids and the precursor of all estrogens, the primary and most well-known androgen is testosterone. Dihydrotestosterone and androstenedione are less known generally, but are of importance in male development. DHT in the embryo life causes differentiation of penis, scrotum, later in life DHT contributes to balding, prostate growth and sebaceous gland activity. Although androgens are described as sex hormones, both males and females have them to varying degrees, as is also true of estrogens. They are one of three types of sex hormones, the others being estrogens like estradiol and progestogens like progesterone, the main subset of androgens, known as adrenal androgens, is composed of 19-carbon steroids synthesized in the zona reticularis, the innermost layer of the adrenal cortex. Adrenal androgens function as weak steroids, and the subset includes dehydroepiandrosterone, dehydroepiandrosterone sulfate, androstenedione, besides testosterone, other androgens include, Dehydroepiandrosterone is a steroid hormone produced in the adrenal cortex from cholesterol. It is the precursor of natural estrogens. DHEA is also called dehydroisoandrosterone or dehydroandrosterone, androstenedione is an androgenic steroid produced by the testes, adrenal cortex, and ovaries. While androstenediones are converted metabolically to testosterone and other androgens, they are also the parent structure of estrone, use of androstenedione as an athletic or bodybuilding supplement has been banned by the International Olympic Committee, as well as other sporting organizations. Androstenediol is the steroid metabolite thought to act as the regulator of gonadotropin secretion. It is found in equal amounts in the plasma and urine of both males and females. Dihydrotestosterone is a metabolite of testosterone, and a potent androgen than testosterone in that it binds more strongly to androgen receptors. It is produced in the skin and reproductive tissue, during mammalian development, the gonads are at first capable of becoming either ovaries or testes. In humans, starting at about week 4, the rudiments are present within the intermediate mesoderm adjacent to the developing kidneys. At about week 6, epithelial sex cords develop within the forming testes, in males, certain Y chromosome genes, particularly SRY, control development of the male phenotype, including conversion of the early bipotential gonad into testes. In males, the sex cords fully invade the developing gonads, the mesoderm-derived epithelial cells of the sex cords in developing testes become the Sertoli cells, which will function to support sperm cell formation

24.
Anabolic steroid
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They are anabolic and increase protein within cells, especially in skeletal muscles. The word anabolic, referring to anabolism, comes from the Greek ἀναβολή anabole and they are one of three types of sex hormone agonists, the others being estrogens like estradiol and progestogens like progesterone. Health risks can be produced by long-term use or excessive doses of AAS and these effects include harmful changes in cholesterol levels, acne, high blood pressure, liver damage, and dangerous changes in the structure of the left ventricle of the heart. Conditions pertaining to hormonal imbalances such as gynecomastia and testicular size reduction may also be caused by AAS and their use is referred to as doping and banned by most major sporting bodies. For many years, AAS have been by far the most detected doping substances in IOC-accredited laboratories, in countries where AAS are controlled substances, there is often a black market in which smuggled, clandestinely manufactured or even counterfeit drugs are sold to users. AAS have largely replaced in this setting by synthetic protein hormones that selectively stimulate growth of blood cell precursors. Growth stimulation, AAS can be used by pediatric endocrinologists to treat children with growth failure, however, the availability of synthetic growth hormone, which has fewer side effects, makes this a secondary treatment. Stimulation of appetite and preservation and increase of mass, AAS have been given to people with chronic wasting conditions such as cancer. Induction of male puberty, Androgens are given to many boys distressed about extreme delay of puberty, Testosterone is now nearly the only androgen used for this purpose and has been shown to increase height, weight, and fat-free mass in boys with delayed puberty. Male contraception, in the form of testosterone enanthate, potential for use in the near-future as a safe, reliable, stimulation of lean body mass and prevention of bone loss in elderly men, as some studies indicate. Hormone replacement for men with low levels of testosterone, also effective in improving libido for elderly males, most steroid users are not athletes. Between 1 million and 3 million people are thought to have misused AAS in the United States, another study found that non-medical use of AAS among college students was at or less than 1%. According to a recent survey,78, the same study found that individuals using AAS for non-medical purposes had a higher employment rate and a higher household income than the general population. AAS users tend to be disillusioned by the portrayal of AAS as deadly in the media, according to one study, AAS users also distrust their physicians and in the sample 56% had not disclosed their AAS use to their physicians. A recent study has shown that long term AAS users were more likely to have symptoms of muscle dysmorphia. A recent study in the Journal of Health Psychology showed that many believed that steroids used in moderation were safe. AAS have been used by men and women in different kinds of professional sports to attain a competitive edge or to assist in recovery from injury. These sports include bodybuilding, weightlifting, shot put and other track and field, cycling, baseball, wrestling, mixed martial arts, boxing, football, such use is prohibited by the rules of the governing bodies of most sports

25.
Methyltestosterone
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Testosterone is a medication and naturally occurring steroid hormone. It is an androgen and anabolic steroid and is used to treat male hypogonadism and it may also be used to increase athletic ability in the form of doping. It is unclear if the use of testosterone for low levels due to aging is beneficial or harmful. Testosterone can be used as a gel or patch that is applied to the skin, injection into a muscle, tablet that is placed in the cheek, common side effects from testosterone medication include acne, swelling, and breast enlargement in males. Serious side effects may include liver toxicity, heart disease, women and children who are exposed may develop virilization. It is recommended that individuals with prostate cancer not use the medication and it can cause harm to the baby if used during pregnancy or breastfeeding. Testosterone was first isolated in 1935, rates of use have increased three times in the United States between 2001 and 2011. It is on the World Health Organizations List of Essential Medicines and it is available as a generic medication. The price depends on the dose and form of the product, the primary use of testosterone is the treatment of males with too little or no natural testosterone production, also termed hypogonadism or hypoandrogenism. This treatment is referred to as hormone replacement therapy, or alternatively and it is used to maintain serum testosterone levels in the normal male range. Decline of testosterone production with age has led to interest in testosterone supplementation, Testosterone deficiency is an abnormally low testosterone production. It may occur because of testicular dysfunction or hypothalamic-pituitary dysfunction and may be congenital or acquired, Testosterone levels may decline gradually with age. The United States Food and Drug Administration stated in 2015 that neither the nor the safety of testosterone supplement have been established for low testosterone levels due to aging. The FDA has required that labels on testosterone include warnings about increased risk of heart attacks, Testosterone supplementation is effective in the short term for hypoactive sexual desire disorder. However, its long term safety is unclear, treating low androgen levels with testosterone is not generally recommended in women when it is due to hypopituitarism, adrenal insufficiency, or following surgical removal of the ovaries. It is also not usually recommended for improving cognition, the risk of heart disease, Testosterone is used as a form of doping among athletes in order to improve performance. Testosterone is classified as an agent and is on the World Anti-Doping Agency List of Prohibited Substances. Anabolic-androgenic steroids, including testosterone and its esters, have also taken to enhance muscle development, strength

26.
Metandienone
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Metandienone was originally developed in 1957 by CIBA and marketed in Germany and the United States. It is currently a controlled substance in the U. S. and UK, metandienone is readily available without a prescription in certain countries such as Mexico, and is also manufactured in Asia and many Eastern European countries. Metandienone was first synthesized in 1956 by researchers at the CIBA laboratories in Basel, CIBA filed for a US patent in 1957, and began marketing the compound as Dianabol in 1958. Beginning soon afterwards in 1959, CIBA collaborated with John Bosley Ziegler to test the effects of Dianabol on professional weightlifters. Ziegler had a relationship with Bob Hoffman, owner of York Barbell Company and coach of the US Olympic weightlifting team. The first tentative experiments were disappointing, for example, AAU Mr. America winner Jim Park reported that its only effect was to give him an instant erection upon seeing any female. However, Ziegler believed that Dianabol had significant potential as an anabolic, during the lead-up to the 1960 Olympics, he proposed to Hoffman that it be administered to top members of the American Olympic team. Hoffman, however, was cautious and later remarked it was too close to give to the men who represent the USA. According to Grimek, apparently, he doesn’t think it will do much good. Instead, Dianabol was given to lower level lifters to investigate its effectiveness. Among the first subjects were John Grimek, Bill March, Charles Vinci, Riecke gained muscle mass and strength rapidly, and reported a constant feeling of euphoria and energy. His results drew enormous interest among other elite weightlifters, and rumors spread that Ziegler had made a breakthrough in his research. He attempted to deflect their curiosity with hints of new isometric and hypnotic techniques, over the course of the next 2 years, Zieglers work with Riecke further explored the new drugs physical and psychological effects. Rieckes performance and mood consistently improved while taking Dianabol, and dramatically declined when he did not take it. John Fair also suggests that Riecke was among the first cases of steroid dependency, at one point mentioning the four times in letter. American football players and coaches were particularly interested in the new anabolic, early adopters included players for Oklahoma University and San Diego Chargers head coach Sid Gillman, who administered Dianabol to his team starting in 1963. In 1965, the FDA pressured CIBA to further document its legitimate medical uses, after CIBAs patent exclusivity period lapsed, other manufacturers began to market generic metandienone in the US. Following further FDA pressure, CIBA withdrew Dianabol in 1983, generic production shut down two years later, when the FDA revoked metandienones approval entirely in 1985

27.
Noretynodrel
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Noretynodrel, or norethynodrel, also known as 17α-ethynyl-19-nor-5-testosterone or as 5-norethisterone, is a steroidal progestin of the 19-nortestosterone group and an isomer of norethisterone. Noretynodrel was introduced in 1957 in Enovid, a formulation of noretynodrel and mestranol. A few years later, in May 1960, Enovid was also approved as the first oral contraceptive, noretynodrel, unlike most progestins but similarly to etynodiol diacetate, has some estrogenic activity. It has little or no androgenic activity, the drug is a relatively weak progestogen, with only about one-tenth of the progestogenic activity of norethisterone, and in relation to this fact, is no longer used in oral contraceptives. Noretynodrel is very related to norethisterone and tibolone, which are the Δ4-isomer. Noretynodrel is metabolized in a similar manner to tibolone, whereas the metabolism of norethisterone differs. Both noretynodrel and tibolone are transformed into 3α- and 3β-hydroxylated metabolites, tibolone is considered to be a prodrug into both its 3α- and 3β-hydroxylated and Δ4-isomerized metabolites. In terms of the PR, noretynodrel possesses only about 6% to 19% of the affinity of norethisterone for the PRA, relative to norethisterone, noretynodrel has 45% to 81% reduced affinity for the androgen receptor. In contrast to norethisterone, noretynodrel is said to have no or only very weak androgenic activity, in accordance, no androgenic effects have been observed with noretynodrel even when used in large dosages for prolonged periods of time in the treatment of women with endometriosis. Additionally, noretynodrel has not been found to virilize female fetuses, in contrast to many other testosterone-derived progestins including ethisterone, norethisterone, however, according to Korn, at least one case of pseudohermaphroditism has been observed that may have been due to noretynodrel. Whereas norethisterone has virtually no affinity for the receptors, noretynodrel shows some. The estrogenic activity of 3α- and 3β-hydroxynoretynodrel has never been assessed, however, while tibolone shows similar affinity for the ERs as noretynodrel, the 3α- and 3β-hydroxylated metabolites of tibolone have several-fold increased affinity for the ERs. As such, the 3α- and 3β-hydroxylated metabolites of noretynodrel may also show increased activity. The Δ4-isomer of tibolone, similarly to norethisterone, is devoid of affinity for the ERs. As such, aromatization likely does not play a role in the activity of tibolone or noretynodrel. However, controversy on this matter exists, and other researchers have suggested that tibolone, relative to other 19-nortestosterone progestins, noretynodrel is said to possess much stronger estrogenic activity. Noretynodrel is a steroid and is also known chemically as 17α-ethynyl-δ5-19-nortestosterone or as 17α-ethynylestr-5-en-17β-ol-3-one. It is a derivative of testosterone that has been ethynylated at the C17α position, demethylated at the C19 position, as such, noretynodrel is also a combined derivative of nandrolone and ethisterone

28.
Etynodiol diacetate
–
It is the 3β, 17β-diacetate ester of etynodiol, and acts as a rapidly converted prodrug to norethisterone, with etynodiol occurring as an intermediate. Etynodiol diacetate has weak androgenic activity, and, unlike most progestins but similarly to norethisterone and noretynodrel, Etynodiol diacetate is virtually inactive in terms of affinity for the progesterone and androgen receptors and acts as a prodrug of etynodiol, which in turn is a prodrug of norethisterone. Reduction of norethisterone affords the 3, 17-diol, acetylation of the 3β, 17β-diol affords Etynodiol diacetate, one of the most potent oral progestins. Methynodiol diacetate Norethisterone acetate Norethisterone enanthate Lynestrenol

29.
Tibolone
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It is used mainly for treatment of endometriosis, as well as hormone replacement therapy in post-menopausal women. Tibolone has similar or greater efficacy compared to older hormone replacement drugs and it has also been investigated as a possible treatment for female sexual dysfunction. Tibolone is a 19-nortestosterone derivative and is related structurally to other 19-nortestosterone progestins and it is the 7α-methyl derivative of noretynodrel. Its two major metabolites, 3α-hydroxytibolone and 3β-hydroxytibolone, act as potent, fully activating agonists of the estrogen receptor. Tibolone and its metabolite Δ4-tibolone act as agonists of the progesterone and androgen receptors, while 3α-hydroxytibolone and 3β-hydroxytibolone, conversely, lastly, tibolone, 3α-hydroxytibolone, and 3β-hydroxytibolone act as antagonists of the glucocorticoid and mineralocorticoid receptors, with preference for the mineralocorticoid receptor. Tibolone has tissue-selective estrogenic effects, with effects in bone, the brain, and the vagina. As such, to distinguish it from SERMs, tibolone has been described as a selective tissue estrogenic activity regulator, tibolone is also known chemically as 7α-methyl-17α-ethynyl-19-nor-δ5-testosterone or as 7α-methyl-17α-ethynyl-17β-hydroxy-19-norandrost-5-en-3-one, as well as 7α-methylnoretynodrel. Tibolone was developed in the 1960s and it was first introduced in the Netherlands in 1988, and was subsequently introduced in the United Kingdom in 1991